Abstract: Al_0.1CoCrFeNi high-entropy alloy bar was subjected to quasi-static torsion. Using XRD, SEM, EBSD, nanoindentation and quasi-static tensile experiment, the gradient microstructure and mechanical properties of the sample after torsion were systematically investigated.In addition to grain refinement, the gradient microstructure also includes dislocations and twin substructures whose contents increase from center to edge. The tensile test shows that the tensile plate after torsion can significantly improve tensile strength while remaining good ductility due to gradient microstructure and the higher work-hardening ability. Therefore, the gradient strain, additional work-hardening ability and back stress effect lead to an excellent combination of strength and plasticity.In addition, the nanohardness continues to increase along the radial direction, i.e., an obvious gradient distribution, which is mainly attributed to grain-boundary strengthening and work-hardening effect.